(a) Field of the Invention
The present invention relates to an inkjet alignment layer printing apparatus and a printing method of the alignment layer.
(b) Description of Related Art
A liquid crystal display (LCD) is a widely-used flat panel display that includes a pair of panels provided with field generating electrodes and a liquid crystal (LC) layer having dielectric anisotropy that is disposed between the two panels. Each panel includes an alignment layer.
The field generating electrodes generally include a plurality of pixel electrodes connected to switching elements such as thin film transistors (TFTs) to be supplied with data voltages and a common electrode covering an entire surface of a panel and supplied with a common voltage. A pair of field generating electrodes that generate the electric field in cooperation with each other and an LC disposed therebetween is called an LC capacitor.
Voltages are applied to the field generating electrodes to generate an electric field in the LC layer, and the strength of the electric field can be controlled by adjusting the voltage across the LC capacitor. Since the electric field determines the orientations of LC molecules and the molecular orientations determine the transmittance of light passing through the LC layer, the light transmittance is adjusted by controlling the applied voltages. By adjusting the light transmittance, the desired images are obtained.
The alignment layers are formed on a side of the panels adjacent to the LC layer to define the initial alignment of the LC molecules, by spin coating or flexo printing.
An alignment layer printing apparatus for forming the alignment layers using flexo printing includes a plurality of rolls such as an anilox roll and a printing roll engaged with each other, and plates made of a rubber and attached to the rolls. However, as the size of the panels and mother substrates for making the panels become larger, the size and the weight of the rolls and the plates increase, making the manufacturing of the alignment layer printing apparatus difficult.